This is being circulated by Red State, National Review, and the Weekly Standard, all of which are blogs I respect. I do not know, incontrovertibly, that this audio is legit, and the U2 music is pretty corny, but the explanation given by the (Barack Obama) voice seems consistent with the top ten reasons (as documented by Jill Stanek – see especially #6 and #9) that Barack Obama voted against the Born Alive Infant Protection Act three times.
An original source document: This is the transcript of the Illinois State Senate session on March 30, 2001. Scroll down to pages 84-90 (or just do a text search on “Obama”) to read Obama’s concerns with Senate Bills 1093-1095, all of which are quite similar. Bill 1095 is the Born Alive Infant Protection Act (BAIPA). Each time, it is Obama, and only Obama, who raises concerns. [Note that while BAIPA passed on March 30, 2001, it later died in committee.]